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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 | /**
* MP3 demuxer
*/
import ID3 from '../demux/id3';
import { logger } from '../utils/logger';
import MpegAudio from './mpegaudio';
class MP3Demuxer {
constructor (observer, remuxer, config) {
this.observer = observer;
this.config = config;
this.remuxer = remuxer;
}
resetInitSegment (initSegment, audioCodec, videoCodec, duration) {
this._audioTrack = { container: 'audio/mpeg', type: 'audio', id: -1, sequenceNumber: 0, isAAC: false, samples: [], len: 0, manifestCodec: audioCodec, duration: duration, inputTimeScale: 90000 };
}
resetTimeStamp () {
}
static probe (data) {
// check if data contains ID3 timestamp and MPEG sync word
let offset, length;
let id3Data = ID3.getID3Data(data, 0);
if (id3Data && ID3.getTimeStamp(id3Data) !== undefined) {
// Look for MPEG header | 1111 1111 | 111X XYZX | where X can be either 0 or 1 and Y or Z should be 1
// Layer bits (position 14 and 15) in header should be always different from 0 (Layer I or Layer II or Layer III)
// More info http://www.mp3-tech.org/programmer/frame_header.html
for (offset = id3Data.length, length = Math.min(data.length - 1, offset + 100); offset < length; offset++) {
if (MpegAudio.probe(data, offset)) {
logger.log('MPEG Audio sync word found !');
return true;
}
}
}
return false;
}
// feed incoming data to the front of the parsing pipeline
append (data, timeOffset, contiguous, accurateTimeOffset) {
let id3Data = ID3.getID3Data(data, 0);
let timestamp = ID3.getTimeStamp(id3Data);
let pts = timestamp ? 90 * timestamp : timeOffset * 90000;
let offset = id3Data.length;
let length = data.length;
let frameIndex = 0, stamp = 0;
let track = this._audioTrack;
let id3Samples = [{ pts: pts, dts: pts, data: id3Data }];
while (offset < length) {
if (MpegAudio.isHeader(data, offset)) {
let frame = MpegAudio.appendFrame(track, data, offset, pts, frameIndex);
if (frame) {
offset += frame.length;
stamp = frame.sample.pts;
frameIndex++;
} else {
// logger.log('Unable to parse Mpeg audio frame');
break;
}
} else if (ID3.isHeader(data, offset)) {
id3Data = ID3.getID3Data(data, offset);
id3Samples.push({ pts: stamp, dts: stamp, data: id3Data });
offset += id3Data.length;
} else {
// nothing found, keep looking
offset++;
}
}
this.remuxer.remux(track,
{ samples: [] },
{ samples: id3Samples, inputTimeScale: 90000 },
{ samples: [] },
timeOffset,
contiguous,
accurateTimeOffset);
}
destroy () {
}
}
export default MP3Demuxer;
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